Use an ESP32-C5 in place of the RX5808 receiver in an FPVGate lap timer.
The ESP32-C5 has a 5 GHz radio that can receive most 5.8 GHz FPV channels. This firmware makes it behave exactly like an RX5808 module: FPVGate tunes it over the usual three-wire bus, and it sends the signal strength back as a voltage on the RSSI pin. FPVGate needs no changes.
FPVGate detecting repeated passes with the C5 as its receiver. The shaded green regions mark detections; the horizontal lines show the gate thresholds.
Working on the bench with a Waveshare ESP32-C5-Zero and an FPVGate timer built on a Seeed XIAO ESP32-S3.
| Result | |
|---|---|
| Picks up the tuned channel | With a VTX on R4 at 50 cm: -12 to -24 dBm on R4, -93 to -97 dBm on other channels, and -76 dBm with the VTX off |
| Response | Sharp rises and falls on FPVGate's graph |
| Stability | A steady reading, within 3 dB, with the VTX left on for a minute |
| Tuning from FPVGate | FPVGate's channel changes arrive and the C5 follows them |
| Unit tests | About 1,300 checks, all passing |
Still to do: compare lap times with an RX5808 over many real passes, and test more ESP32-C5 boards.
- Behaves like an RX5808: takes RX5808 tuning commands, answers FPVGate's frequency check, and handles power-down and reset.
- Analog RSSI output, and the RSSI can also be read digitally over the bus.
- Fast, clean RSSI: a live signal-strength reading from the radio, with short Wi-Fi bursts filtered out and the VTX's own short dips bridged, without smoothing off the edges.
- Calibration and a soft ceiling: fit your real signal levels to FPVGate's 0 to 255 scale, and optionally make strong signals bunch together like a saturating RX5808.
- Serial console: scan channels, watch the signal live, calibrate and save, over USB with no FPVGate needed.
- Channels: all of Raceband (R8 included), bands A, B and F, and E1-E5. Channels outside the Wi-Fi bands (R8, E6-E8, L) are tuned directly in the radio; see Extended tuning.
git clone https://github.com/LouisHitchcock/FPVGateC5RX.git
cd FPVGateC5RX\firmware
pio run -e waveshare_c5_zero -t upload --upload-port COM29Then follow docs/GETTING_STARTED.md to test the radio over USB, wire it to FPVGate and calibrate it.
| Document | Contents |
|---|---|
| Getting started | Start here. Flashing, testing, wiring to FPVGate, calibration, troubleshooting. |
| Console | Every serial console command |
| Hardware | Wiring, and why each resistor and capacitor is needed |
| How it works | The design: the bus, the radio, the RSSI pipeline |
| Extended tuning | R8 and other channels outside the Wi-Fi bands, the live signal-RSSI reading, and the bench results |
| Licensing | The licence, commercial licensing, and why it isn't GPL |
| Provenance | Where each technical fact came from |
firmware/ PlatformIO project: core/ (portable C++, unit-tested) and src/ (ESP32-C5 code)
test/ Unit tests that run on a PC: bash test/run.sh (needs g++)
tools/ c5cmd.py, for sending console commands from a script
docs/ Documentation
Free for non-commercial use under CC BY-NC-SA 4.0, the same licence as FPVGate.
Commercial use, such as selling hardware or firmware or running a paid service, needs a commercial licence. To ask, email louishitchcock@gmail.com.
This firmware was written from scratch and isn't GPL: no code from the GPL projects that use the ESP32-C5's radio for FPV was used. The reasoning, and the licences of the third-party parts (Arduino-ESP32 core: LGPL-2.1; ESP-IDF: Apache-2.0), are in docs/LICENSING.md.
Copyright 2026 Louis Hitchcock